Ultrasonic cellular tissue screening system

ABSTRACT

A system for screening breast tissue is disclosed. The system comprises an ultrasound probe and a carrier adapted to support the ultrasound probe and to progressively move the probe over the breast tissue. A pad is employed to cover the nipple of the breast tissue, and a fabric covering is adapted to hold the breast tissue and the pad in place as the probe is moved over the breast tissue.

PRIORITY

Priority is claimed as a continuation application to U.S. patentapplication Ser. No. 10/328,259, filed Dec. 23, 2002, now U.S. Pat. No.7,445,599, which is a divisional of Ser. No. 09/687,128, now U.S. Pat.No. 6,524,246, filed Oct. 13, 2000, the disclosures of which areincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The field of the present invention is ultrasonic scanning anddiagnostics for cellular tissue.

2. Background of the Invention

Ultrasonic probes have been used for scanning cellular tissue for manyyears. Presently, any medical ultrasound examination, whether of theheart, pelvis, abdomen, soft tissues or any other system, is usuallydisplayed as a number of individual frames or pictures from a studyperformed in a dynamic movie like manner. The usefulness of the scan,however, is dependent on the skill of the operator, who manipulates theprobe by hand while watching the scan images on a monitor to identifyareas of interest. Once these areas are identified, the operator usuallyrecords single or multiple single scan images showing those areas.

Because the operator must choose a few frames from the large numbergenerated during the scan, the process is open to error. The operatormay fail to select an image of an important finding, or may select animage that misrepresents the overall findings. In addition, since theoperator is manipulating the probe by hand, and the speed of the probeover the tissue cannot be correlated with the image capture rate of theprobe, the coverage of the scanned tissue is somewhat haphazard. As aresult, the operator does not record a series of images that represent acontiguous and complete set of images for the entire scanned tissue. Nordoes the manual operation of the probe allow for entirely uniformcoverage of the tissue, even if multiple passes are used.

A second method of recording ultrasonic examinations is used for dynamicexaminations such as echocardiography, where a dynamic recording is madeon videotape. Unfortunately, this analog method is not matched to thedigital sonographic recording of individual frames. Consequently, thereis a great loss of detail that prevents the evaluation of individualframes, which limits the usefulness of the videotape for diagnosingtissue anomalies. In addition, the use of separate videotapes forindividual patients is expensive, and creates a storage problem becauseof the bulkiness of the tapes. The interpreting physician has no way tovary the speed of playback or to vary the size of the images. Nor canthe physician vary the inherent contrast and brightness of the images,only the monitor settings. These difficulties lengthen the review timeand prevent optimum viewing.

Specific to screening asymptomatic women for occult breast cancer, thereare two methods presently in widespread use, physical examination andmammography. Both of these methods are imperfect. Physical examination,whether performed by the woman herself or by a physician or other healthcare provider, usually cannot detect cancers smaller than ½ inch indiameter. Some cancers have to be many times larger to be detected.Mammography is unable to detect as many as 30 percent of cancers smallerthan ½ inch. About 5 to 10 percent of larger cancers aremammographically occult. Mammograms also use radiation and necessitatepainful compression of the breasts, which discourage women from havingroutine mammograms.

Although not well recognized by the medical community, ultrasound isvery proficient at diagnosing breast cancers if the location of theabnormality is first discovered by another modality, such as mammographyor physical examination. When using ultrasound as a screening method forthe entire breast, however, malignancies are usually difficult to pickout of the background tissue. In the past there have been two schemes touse ultrasound for breast screening, but they failed to gain acceptancedue to their unacceptably low success rate in finding cancers.

One method was a water bath system with multiple ultrasound probes andthe breast in a water bath that allowed generation of images of thewhole breast in consecutive slices. These slices could be viewed insequence at a rate of one every ten seconds.

The second method was to videotape record the scanning performed by atechnician examining the entire breast. This method had the disadvantageof being somewhat haphazard in breast coverage. The variable speed ofmanual motion does not allow the tissue to be uniformly imaged becausethe speed is not synchronized to the frame capture rate of theultrasound probe. Videotaping also results in a degradation of theimages for the reasons described above.

To date, no method has been developed to uniformly and reliably useultrasound probes to create a contiguous and complete set of scan imagesfor an entire area of cellular tissue, such as a human breast.Ultrasound is usually used to investigate areas of interest in cellulartissue that have already been identified by other screening methods suchas mammograms, x-rays, and MRI-scans. Ultrasound is not ordinarily usedas a screening tool for cellular tissue anomalies.

SUMMARY OF THE INVENTION

The present invention is directed to an improved system of ultrasonicscanning and diagnostics of breast tissue. A sequence of cross-sectionalultrasonic images of tissue are generated. To create the appropriateenvironment for such scanning, a fabric covering adapted for holding thebreast tissue in place accommodates an ultrasonic coupling agent toabsorb the agent for conducting ultrasonic energy with minimalinterference. The covering may be preimpregnated, may include a patternusable by an optical measurement sensor and may be constructed for easyremoval. A pad which is ultrasonically conductive may be placed beneaththe fabric covering to cover the breast nipple.

Accordingly, it is an object of the present invention to provide asystem and method that will allow cellular tissue to be reliablyscreened for anomalies by ultrasonic scanning. Other and further objectsand advantages will appear hereafter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing the elements of a cellular tissuescreening tool and its interconnections.

FIG. 2 depicts a plan view of a patient platform and probe carrier.

FIG. 3 depicts a side view of a patient platform and probe carrier.

FIG. 4 depicts an end view of a patient platform, and the probe carrierholding an ultrasonic probe.

FIG. 4A depicts a portion of a probe carrier holding an ultrasonicprobe.

FIG. 5 is a schematic diagram showing a plurality of scan rows of scanrow images made of a right lateral scan of a human breast.

FIG. 6 is a flow chart describing how the viewing program on thecomputer acquires data from the ultrasonic scanner, converts it intodigital image data that can be used by the viewing program, and createsan image file.

FIG. 7 is a flow chart describing how a user interface of the viewingprogram operates to acquire data from the ultrasonic scanner and createan image file on the computer.

FIG. 8 is a schematic of a preferred embodiment of an image filecontaining a plurality of scan row images.

FIG. 9 is a flow chart describing how the user interface of the viewingprogram operates during playback of images on the computer.

FIG. 10 is a flow chart describing the operation of the viewingprogram's location function.

FIG. 11A is a front view of a fabric covering.

FIG. 11B is a rear view of a fabric covering.

FIG. 12A is a plan view of a nipple pad.

FIG. 12B is a side view of a nipple pad.

FIG. 12C is a perspective view of a nipple pad.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

As shown in FIG. 1, a preferred embodiment is comprised of a patientplatform 2 to steady the patient and provide a base for the supportmember 4, the probe carrier 5 connected with the support member 4 thatis capable of translational movement to guide the probe across thetissue to be scanned, a standard medical ultrasound device 6 with anassociated probe 8, a remote control device 10 that operates the probecarrier 4, a standard computer 12, a connection device 14 between theultrasound device 6 and the computer 12, and a viewing program thatobtains images from the ultrasound device and converts them into imagescompatible with the viewing program and displays the images. The medicalultrasound scanning device 6 with associated probe 8, computer 12, andconnection device 14 are commercially available.

The mechanical carrier 4 holding the ultrasound probe 8 can be connectedwith the ultrasound scanner 6. Synchronization between the probe holdermechanical carrier 4 and the ultrasound scanner 6 can be employed whilerecording the scans.

1. Probe Carrier

In order to obtain substantially parallel and contiguous images, amechanical device holding the ultrasound probe 8 propels the probeacross the tissue to be scanned at a uniform rate. In a preferredembodiment shown in FIG. 3, the probe carrier is mounted to a patientplatform 16 that steadies the patient during the exam and acts as a basefor the mechanical probe carrier. The carrier carriage 18 shown in FIGS.2 and 3 is comprised of two parallel vertical members attached to rails20 beneath the platform and a horizontal member that is attached to thetop of the two vertical members, as shown in FIG. 4. The rails 20 allowthe carriage 18 to move along the length of the platform, or the x-axis,as shown in FIGS. 2 and 3. Attached to the horizontal member between thetwo vertical members is another vertical member, called the carrier arm22, with the carrier 24 holding an ultrasound probe 8 at its lower end.The carrier arm 22 is attached in such a manner that allows it to movealong both the y-axis and the z-axis, so that it can move both acrossthe patient and nearer/further from the patient on the platform, asshown in FIG. 4. The carrier 24 itself is articulated to hold the probeat any desired angle relative to the patient by rotating about the x andy axes. The carrier 24 holds the probe 8 at a fixed angle duringscanning. In another embodiment, the carrier 24 dynamically angles theprobe 8 during the scanning process to keep it perpendicular to thepatient's skin (or any other preferred orientation).

To protect the carriage assembly when not in use, and to prevent thepatient from becoming entangled in it when first lying on the platform,the assembly is housed in a “garage” 26 at one end of the platform 16.In a preferred embodiment, the carriage 18 is propelled along the x-axisof the platform 16 during scanning by one or more motors that arecontrolled by a microprocessor. The carrier arm 22 is also moved alongits two axes during scanning by one or more motors controlled by one ormore microprocessors. The microprocessor(s) can be separate from thecomputer that operates the viewing program (described below), or thecomputer can be used for this purpose. The carrier arm 22 moves alongthe z-axis to maintain consistent contact between the probe 8 and thepatient's skin during scanning. The carrier arm 22 maintains a constantpressure of the probe 8 on the patient, with a user-selected presetvalue. This pressure is monitored during the scan and an overridefunction will move the carrier arm 22 up and away from the patient inthe z-axis if a maximum pressure level is detected. In anotherembodiment, the operator will maintain the pressure manually during thescanning process, and the pressure may be measured using pressuretransducer(s) in close proximity to the probe head. The carrier arm 22will move upward to clear the patient at the end of the scan. A manualoverride on the remote control 10 is also available to move the carrierarm 22 away from the patient when there is a panic or emergencysituation.

In other embodiments, the carriage and carrier arm can be either on aparallel track arrangement (one sided or multi-sided), or be comprisedof an articulating arm or some other contrivance, located over,underneath or adjacent to the patient (with or without the use of apatient platform) positioned either upright or prone. The carrier armneed not be supported by a carriage assembly connected to the patientplatform, but could be independently suspended from the ceiling, wall,or floor. The carrier mechanism could be similar to carriage mechanismscurrently used to support x-ray machines, with means added to providethe requisite movement of the probe. The probe may be supported andpropelled by the mechanical carrier by any means (manually,mechanically, electrically, hydraulically, pneumatically or by any othermeans, with or without control feedback), or any combination of methods.These methods, singularly or combined may be utilized to control theprobe in the X, Y and Z-axes. Gravity may also be employed to providethe requisite pressure of the probe on the patient, or assist in thepropulsion of the probe across the tissue.

The probe may be designed as a permanent or removable component of themechanical carrier. The carrier may be designed with or without anonboard integrated ultrasound machine, ultrasound probe, and orultrasound probe interface.

The carrier 24 can be articulated to change the angular position of theprobe 8 prior to or during scanning either manually, or by one or moremotors controlled by one or more microprocessors. The microprocessor(s)can be separate from the computer that operates the viewing program(described below), or the computer can be used for this purpose. Thepitch axis tilts the probe 8 forward and backward, rotating it about they-axis, and the roll axis tilts the probe 8 left and right, rotating itabout the x-axis. The pitch and roll axes maintain full contact betweenthe probe and the skin surface by maintaining the probe 8 at aperpendicular angle to the skin, to allow for optimal ultrasonicimaging.

In an embodiment where the probe's angular position is adjustedautomatically during scanning, the pitch and roll adjustments aretriggered by one or more displacement transducers positioned around theultrasound probe 8. In this embodiment, all the data related to theposition and angle of the probe 8 are provided to the viewing program toallow the images to be correlated with their corresponding location onthe patient. The position data allow the program to compensate for theoverlapping of, or gaps between images. The measurement system can be byany means or convention and may consist of any or all of X, Y, Z-axesand/or the probe angular position.

The speed of the carrier 24 holding the probe 8 is precisely controlledby a microprocessor, and the speed is correlated with the capture rateof the ultrasonic scanning device 6. The uniform speed of the carrier 24results in images that are uniformly spaced, which allows the viewingprogram (discussed below) to calculate the position of a selected pointon any image. In an embodiment where the probe is held at a fixed angleduring the scan, the uniform spacing is all that is necessary todetermine the position of each frame of the scan on the patient. Theultrasound scanning device 6 acts as a controller in communication withthe probe 8 to sequentially activate the probe 8 as it moves across thetissue, but any other controller could be used to activate the probe,including a computer linked to the probe or the scanning device or both.

When used for breast tissue scanning, the operator will determine theamount of area of the breast for scanning. In current practice, thewidth of the tissue scanned by the ultrasound probe is generally toosmall to capture an image of an entire organ, such as the breast. As aresult, several adjacent passes are performed to provide completecoverage. Each pass (called a scan row) will have some overlap with thepreceding pass, to achieve full coverage and eliminate the potential formissing features at the fringes of the scan. Prior to each successivepass, the carrier arm 22 lifts away from the patient, moves along they-axis across the breast and along the x-axis to the top of the breastto position itself for the next scan row, then lowers itself along thez-axis onto the patient.

A scan row contains a plurality of individual images or frames,typically about 200 to 300 for a breast. FIG. 5 depicts how the frames28 in scan rows 30 are aligned on a typical breast scan, but forclarity, no overlap is shown. A scan row 30 can be thought of as a stackof photographic slides, each slide representing an individual frame 28.The frames 28 are evenly spaced. This may be accomplished by uniformmotion of the probe 8 and uniform timing of the scans. The frames aremost conveniently substantially parallel to each other.

In another embodiment, the probe's 8 angular position is dynamicallyadjusted during scanning to follow the contours of the tissue beingscanned. In that embodiment, the tops of the frames are evenly spaced,and the tissue contours will be sufficiently gentle that adjacent frameswill remain substantially parallel to each other, although they maydiffer by as much as a few degrees. Although adjacent frames within asingle scan row are substantially parallel, frames may becomeprogressively less parallel as they are separated by an increasingnumber of frames. Frames in two adjacent scan rows are not necessarilysubstantially parallel.

In a preferred embodiment, two breasts are scanned in four segments,each segment consisting of one-half of a breast. Each segment consistsof multiple scan rows 30, with the first scan row aligned at the centerof the breast over the nipple and successive scan rows beingprogressively further from the nipple. FIG. 5 depicts a series of scanrows 30 that make up one segment. In other embodiments, each breast maybe scanned in one or more segments, with the scan rows progressingacross the entire breast from lateral to medial, or vice-versa.

2. Viewing Program

The viewing program preferably has the following overall features:

-   -   a) It allows the entry and storage of demographic and other        written data about each patient.    -   b) It extracts multiple series of the scanning data from the        ultrasound scanning device either as a single image, a completed        data set from a cine loop or as real time continuous data from        video streaming.    -   c) It assembles this data into a single or a number of        individual frames for viewing.    -   d) It may present the multiple data series as descriptive titles        on a content page for subsequent review by the operator.    -   e) In the case above, when each descriptive title is selected,        the corresponding data series is loaded and displayed by the        viewer.    -   f) It is able to present the frames from each data set as        individual images that are displayed on a monitor at a variable        rate. This rate can be sufficiently fast to impart a movie or        cine like quality to the images. The frames can be also        displayed at a slow rate or even as still pictures for more        intense study.    -   g) It is able to display the images at variable magnification        and with a variety of imaging enhancements that make anomalies        more pronounced and visible, including variable contrast and        brightness, gamma correction, etc.    -   h) It acts as a recorder, able to store the information from        each patient scan on a data storage device such as a computer        hard disk and on any temporary or permanent data storage device        such as compact disks (CD's).    -   i) Along with the patient scan data, it may incorporate a stand        alone viewer program on each CD or other storage media.    -   j) It allows the transfer of single or multiple images to the        Internet, printers or other image programs, such as PowerPoint        or PhotoShop.    -   k) It allows for the translation of the scan data into the DICOM        format for use by other proprietary software.    -   l) During image review, it emits an audible signal, a visual        signal, or both, that identifies the end of each scan row,        segment, and breast, to identify the relative position within        the scan data without requiring the user to look away from the        images in order to assess the relative position within the image        sequence.

A preferred embodiment of the viewing program (or viewer) is astreamlined, monolithic, 32 bit Windows application designed to run onWindows 95, Windows 98, NT 4, and Windows 2000. A preferred embodimentis implemented to interface with and acquire data from the GeneralElectric Logiq 700 medical ultrasound scanner. The viewing programcould, of course, be written to run on other types of computer systemsand future versions of operating systems, and to interface with othertypes of scanning devices. As used in the claims, “computer” genericallyrefers to any suitable device using one or more microprocessors toprocess data.

The viewing program's monolithic structure and relatively small sizeallow it to be bundled with the image data for ease of transport andviewing flexibility. In most cases, complete scan data for a patient andthe program can be placed on a single CD, allowing the user to transporta number of patient scans in a relatively small package, and view themon any computer that is compatible with the software on the CD. Althoughit would be even more convenient to transmit scans via e-mail, thecurrent speed and size limitations of e-mail make sending the entirescan impractical. If desired, however, the viewing program can selectsmall segments of the scan data and bundle it with the viewing program,for a small data package that is practical to send via current e-mailsystems. Other delivery options could also be utilized, such asstreaming video over the internet, or discrete file downloads using filecompression to speed download time. To satisfy medical regulatoryrequirements, a lossless compression technique should be used, such asPortable Network Graphics (PNG), or other lossless schemes.

In other embodiments, the viewing program could be designed to operatesolely on a computer on which it resides, or it could be resident on aserver in a client-server environment. The program could also benon-monolithic, using Java or a similar language, in a network-centricenvironment. Given the rate at which software programming and computinghardware are developing, there are limitless variations of how toimplement the software and hardware to achieve the desired result of theviewing program.

In a preferred embodiment shown in FIG. 1, the viewer program controlsthe scanning operation and data offloading via a connection device 14,such as a network TCP/IP interface. Other connection devices could beused, or with certain scanners, none may be needed. The General ElectricLogiq 700 ultrasonic scanning device has an internal buffer that canstore a finite amount of image data before offloading is required toclear the buffer for another scan. Other scanning devices have no suchbuffer, but instead provide an output of streaming data as the scan isbeing performed. Although a preferred embodiment uses a scanning devicewith a buffer, the program is capable of acquiring image data fromscanning devices that continuously offload streaming data. Otherembodiments with different data outputs from the scanning device canalso be used with the viewing program.

In a preferred embodiment, the computer acts as a receiver and recorderfor the ultrasonic images obtained from the ultrasonic scanning device.As shown in FIG. 6, a preferred embodiment uses a handshake sequencebetween the viewer and scanner to begin the scan acquisition process 32.The viewer then invokes the scanner to clear its internal frame buffer34 and then to acquire a scan row to its internal buffer 36. The viewerfreezes the scanner buffer 38, determines the number of frames in thebuffer, their dimensions and pixel format 40, initializes a new scan rowin the image file 42, reads individual frames from the buffer 44, countsthe frame format 46 and writes them into the image file 48 on a datastorage device. It then repeats the acquisition process until all theframes in the scan row are processed 50, and terminates the scan row inthe file 52. It then starts all over with additional scan rows until theentire scan is acquired in the image file 54. A preferred embodiment ofthe viewer uses a proprietary image file format, which contains a headerfor patient information and scan information (“image file”). In anotherembodiment, the viewing program converts the image data into a DICOMformat, which also contains a header for patient information and scaninformation. DICOM stands for “Digital Imaging and COmmunications inMedicine,” and is a standard developed by ACR-NEMA (American College ofRadiology-National Electrical Manufacturer's Association) forcommunications between medical imaging devices.

FIG. 7 is a flow chart showing the user interface for the data transferprocess from the scanner to the computer. The user creates a new file bychoosing from the file menu 56, specifies a name for the new file 58,enters the patient data and relevant information 60, makes a selectionfrom the data menu 62, and specifies what segment of the breast is aboutto be acquired 64. The user then begins the acquisition process 66, andframes are then offloaded sequentially from the scanners frame buffervia a connection device 14, such as a network interface, thennormalized, compressed losslessly (if desired) and written sequentiallyto the image file, said file recorded on a data storage device. When allbuffered frames are processed, the viewer terminates the constructed rowin the image file 68. Another scan row can then be acquired and so on,or the interface to the scanner may be terminated 70.

For offloading streaming data, the program performs a real-timewrite-through. The program queries the scanner for the image formatbefore beginning the acquisition. Then it buffers a single frame at atime and writes that one frame to a data storage device, beforeobtaining another frame through the sockets interface.

3. Acquiring the Data

In a preferred embodiment, the viewer creates (and subsequentlydisplays) proprietary image files, the format of which consists of afile header 72, a patient information block 74, and zero or more blocksof scan row frames 76, as shown in FIG. 8. The patient information block74 contains not only information about the patient, but also informationabout the scan itself, such as the depth and width of the scan, lengthof the scan row, speed of the carrier during the scan, the number offrames per second captured by the scanner, the spacing between eachframe, etc.

In another embodiment where the probe's angular position is dynamicallyadjusted during the scan, the viewer program records on a data storagedevice the angular position of each frame and other information for eachframe. The angular position data can be provided to the viewer programthough the scanner 6, from sensors attached to the probe 8 or thecarrier 5, or from an intermediary computer program that gathers thisdata.

Rows appear in the image file in the order they are acquired, notnecessarily the order in which they will ultimately be displayed by theviewer. Any number of scan rows may be included in an image file andthere is no limit to the size of an image file. The data in an imagefile are laid out in such a manner that frames within a row are advancedin the order in which they will be displayed. This enables the viewer todo efficient read ahead buffering during display for optimal viewingsmoothness.

The viewer is implemented to be largely independent of the particularscanner hardware with which it is paired. A specific module written foreach scanner is responsible for “normalizing” data from the internalformat used by that particular scanner to the format used within animage file. Scan row frame elements stored in an image file are writtenin a format optimized for rapid rendering during display. In a preferredembodiment, the viewer is run on computers using a WIN 32 operatingsystem, and scan frames are written to image files in an 8 bit formatthat closely mirrors 8-bit grayscale Windows DIB (device-independentbitmap) format. This allows the images to be efficiently displayed on aWindows computer with practically no routine translation.

A preferred embodiment pairs the viewer program with the GeneralElectric Logiq 700 ultrasound scanner. To translate frame data from theformat used internally by the Logiq 700 or any other scanner, eachspecific normalizing filter performs several operations to the formatused by the viewer when creating image files. In the Logiq 700, theseoperations include the following:

-   -   1. Byte #3 (the fourth byte) of every D-word is stripped    -   2. Transparent color value 255 is normalized to 0    -   3. Scan lines are inverted    -   4. Byte ordering is changed from “Big Endian” to “Little Endian”    -   5. Scan lines are aligned to 4-byte boundaries

When interfacing with a different scanner device, differentnormalization operations would be appropriate.

4. Displaying the Images

After acquiring, converting, and storing the scan data, the second majortask of the viewer is to display the scan images. The viewer opens apreviously created image file and renders sequential scan row frameswithin its interface in a “movie like” manner. In a preferred embodimentfor breast cancer screening, a breast can be divided into two parts;from the nipple toward the axilla is the lateral half, and from thenipple toward the sternum is the medial half. A set of scan rows foreach breast half is called a “segment,” and thus there are four segmentsfor two complete breast scans. The viewer arranges all scan rows suchthat they are displayed beginning with right lateral scan rows (arrangedsuch that subsequent right lateral rows are progressively more lateral),and then proceeding to right medial scan rows (arranged such thatsubsequent rows are progressively more medial). The viewer then proceedsto left medial scan rows, and then to left lateral scan rows. Althoughthe above arrangement of the scan rows is implemented in a preferredembodiment, different arrangements could be used in other embodiments.

The viewer's user interface provides access to these features andcapabilities:

-   -   1. Play, pause, and reset scan row playback    -   2. Step forward and backward between sequential frames    -   3. Adjust playback frame rate    -   4. Jump forward and backward between scan rows    -   5. Export single frames and sets of frames as standard bit        mapped images    -   6. Select a start point and end point in the frame sequence and        loop playback over that selected frame scan    -   7. Adjust the brightness and contrast of displayed frames    -   8. Apply imaging enhancements to make features or anomalies more        visible    -   9. Print single frames and sets of frames    -   10. Measure features displayed on certain frames, given the        physical height and width of the frames    -   11. Calculate the physical location of a point of interest (POI)        on a particular frame given a reference point (RP) (on the same        frame or a different frame), the physical dimensions of the        frames, the Z coordinate spacing between frames and the X        coordinate overlap of frames on subsequent scan rows    -   12. Alter the frame magnification

The user interface for the viewing program looks and operates in largelythe same manner as commercially available digital video players, such asMicrosoft Windows Media Player, with buttons for Play, Pause, Stop, aslider bar to move back and forth within segments, etc. The playbackfeatures utilize standard Windows input/output operations commonly usedin digital video applications. A generalized flow diagram showing theuser interface steps for playback operation is shown in FIG. 9.

One of the viewer features is the ability to determine the physicallocation (on the patient) of any point on any frame given any selectedreference point on the same frame, or on a different frame. For example,if a physician finds an abnormality on one frame, he needs to then beable to locate some prominent feature elsewhere in the frame data, i.e.,the nipple or a temporary mark placed by the operator, and then find theposition of the abnormality relative to that reference point.

The user interface for the location feature operates as shown in theflowchart in FIG. 10. The user marks the point-of-interest (“POI”) on aparticular frame being viewed 78 by double-clicking it with the computermouse 80. An overlapped window then appears, and within that window asmall display pane shows “thumbnail” sized sonograph frames taken fromthe scan rows (actually, the same row “segment”) in which theabnormality lies 82. The user can then traverse through the thumbnailedframes until he locates a reference frame containing a reference point(“RP”) he wishes to use 84. In the case of a breast scan, the RP willoften be the nipple, which can be positively identified by placing aspecial pad over the nipple during the scan, readily identifiable on theviewer image. The user can then mark a point on that reference frameusing the mouse 84. The viewer program immediately calculates the firstposition relative to the reference point 86 and displays the results (inboth textual and graphical format) to the user 88. The user then closesthe dialog box to end the function 90.

To implement the location feature, the viewer takes advantage of thedata known about the scan, which is written in the image file's headeras part of the data acquisition process. Such information includes thewidth of the frame, and the distance between subsequent frames in aparticular scan row, and the offset between scan rows. Within anindividual frame, the location function calculates the position of auser-selected point by proportional math, using the number of image datapoints (pixels) in the height and width, and the size of the frame, tocalculate the distance of the point from the sides of the frame. Theprogram counts the number of pixels across the width of the frame, thenthe user-selected pixel position number is multiplied by the frame widthand divided by the total number of pixels. For example, assuming theframe width is 4 centimeters, the program counts 400 pixels across thatwidth, and the user selected a point at pixel position 100: 100*4cm/400=1 cm. So the selected point is 1 centimeter from the side of theframe. The program then performs a similar calculation to determine theselected point's distance from the top of the frame. FIG. 10 depictsthis process and also shows how the location function determines thedistances and angles from a user-selected point of interest (POI) to auser-selected reference point (RP), using the known values and simpletrigonometry 86. In breast cancer screening, the POI is usually asuspected cancer, and the RP is the nipple.

The uniform motion of the carrier results in evenly spaced frames, andthus the distance from a reference frame to a particular frame iscalculated by counting the number of frames between them and multiplyingby the spacing 86. In addition, the overlap of each scan row is known,and thus if the RP is in a different scan row than the POI, determiningthe location is a simple matter of determining the overlap and measuringthe distance, and using trigonometry to make any angular and remainingdistance calculations 86. Therefore, counting the frames from the RP andtaking into account their overlap provides the location of eachindividual image.

In a preferred embodiment where the angular position of the probe isdynamically adjusted during the scanning process, the viewing programobtains each frame's angular position during the scan, along with theother information described above. Using that information, the programagain uses simple trigonometry to calculate the distances between the RPand the POI.

Another feature of the viewer is its ability to accurately measure thedistance between two user-selected points on a single frame. This allowsthe user to measure anomalies or features found in the images. Theprocess for measuring is very similar to the location function process.Using the known values for frame depth and width, the measuring functionuses proportional math to determine the distance between the two points.To measure diagonally across a frame, proportional math is used todetermine the lengths of the triangle legs, and simple trigonometry isused to calculate the length of the hypotenuse, which is the distancebetween the points.

5. Carrier-Less Embodiment

It is possible to obtain the sequential scans without the use of acarrier. The probe is coupled with sensors to provide both location andorientation data that is correlated with each individual frame. The term“coupled” means the sensors could be attached to the probe itself, orused to track the probe's movement without actual attachment. Thislocation and orientation sensor system can provide feedback to theoperator to move the probe over the tissue at the correct speed, and tostart each scan row in the correct position. This will allowsufficiently complete coverage of the tissue without the need for amechanized carrier. Alternatively, to obtain relatively uniform spacingof the frames, the speed sensor on the probe can signal the ultrasoundscanning device to vary the frame capture rate to match the speed of theprobe as it is moved across the tissue.

This carrier-less embodiment does not necessarily rely on the precisemovement of the carrier to provide uniform spacing between the frames ofa scan row in order to calculate distances between frames. Becauselocation data are available for each frame, the location function of theviewer can use the location information of the POI frame and compare itto the location information of the RP frame, and make the requisitedistance and trigonometric calculations to determine the distances fromthe RP to the POI.

The location and orientation sensor system can be arranged in a varietyof implementations. A simple inclinometer can be used to determine theorientation of the probe in two or three axes. The location of the probecan be tracked by an inertial sensor system, or a laser or infraredsystem, or a radio frequency local positioning system. Alternatively, asimple wheel device could be used to measure distances as well as thespeed the probe is being moved over the tissue. Alternatively, anoptical movement sensor, such as those commonly used in optical mice, ora laser interferometer, could be attached to the probe to track itsmovement. When used for scanning breast tissue in conjunction with acovering, the covering could be made of some type of fabric that iscompatible with an optical movement sensor. All of these systems coulduse a point on the body as a reference location, such as the nipple whenthe system is used for breast scanning.

6. Method for Tissue Screening

The above-described devices, the probe, scanner, carrier, and viewingprogram, can be combined to provide a method to scan for anomalies incellular tissue, such as cancers. The tissue is scanned, and the userviews the images on a computer, rapidly scanning through the images in a“movie-like” fashion. This technique causes any anomalies in the tissueto become visible during the rapid sequential playback, as they distortor disrupt normal fibrous planes or sheets. The user can then run theimages back and forth until the frame containing the anomaly is found,and the user can mark that anomaly and locate it using the locationfunction of the program. Follow-up studies can be performed using thelocation information, including a more focused ultrasound investigation,biopsy, etc.

Individual images can be manipulated using image software such asPhotoshop, using filters and other manipulation techniques to enhancethe appearance of the anomalies and make them more visible. In addition,a variety of image enhancement algorithms are commonly known in the artand the viewer program allows them to be used “on the fly” as the imagesare displayed in rapid succession.

It is anticipated that the image review process could eventually beautomated, once software is developed to identify any anomalies. Ifnecessary, the user could then study the images to determine theaccuracy of the software's identification.

For scanning breast tissue specifically, a preferred methodology is asfollows. The mechanical probe carrier is used, and depending upon thesize of the probe, the breast may be scanned in strips or in itsentirety, in either multiple passes or a single pass, respectively. Thebreast may be scanned with or without a covering. FIGS. 11A and 11B showa bra-like covering 92 that may aid in holding the breast in positionfor screening, as well as assisting in uniform integrity of imagegathering by reducing information loss from ultrasonic shadowing. Thecovering also provides some modesty for the patient. Current ultrasoundtechnology requires the use of sonographic coupling agent, usually agel, to exclude any air between the probe and the skin. Therefore, anysuch covering would have to be capable of absorbing the gel, and berelatively transparent to ultrasonic energy. The covering could bepre-impregnated with the coupling agent, or the agent could be appliedby the operator just prior to the scan, or both. To avoid having thepatient pull a gel-soaked covering over her head after the scan iscompleted, a preferred embodiment of the covering is designed todismantle after use. The covering is equipped with a seam in the back 94that is constructed with chain stitching so that the covering may beremoved by slipping it off the patient's arms. Chain stitching issimilar to that used on bags of dog food and charcoal, where thestitching is easily pulled out just by pulling on one end. The shoulderseams 96 could also be made with chain stitching to further easeremoval. Since a preferred embodiment of the covering is designed to bea single-use item, the covering could be cut off with scissors withoutthe need for special stitching. Zippers, hook and loop (velcro□), orother fasteners could also be used to ease the putting on or removal ofthe covering, and would allow the covering to be re-used. A preferredembodiment uses a stretch fabric for the covering, but any suitablematerial that can conduct or pass through ultrasonic energy could beused.

A nipple pad is placed on each of the patient's nipples to provide areference point on the images. The nipple pad shows up on the scanimages due to its ultrasonic characteristics that distinguish it fromthe breast tissue. The nipple pad has the added benefit of reducingultrasonic shadowing. FIGS. 12A, 12B and 12C depict a preferredembodiment of a nipple pad, which is made of an ultrasonicallyconductive material, such as a solid gel. A preferred embodiment of thepad is approximately 40 mm in diameter and varies in thickness from 1 to4 mm, but other sizes could be used. Larger and thicker gel pads arecommercially available for isolated ultrasound scans, where offsettingthe probe from the tissue is advantageous. As shown in FIGS. 12A, 12Band 12C, the circular pad has a lenticular shape—it is tapered to anedge about the full periphery of the pad, and has a very smooth surface.The edge of the pad is thick enough to resist tearing, yet thin enoughto allow the ultrasound probe to traverse its periphery during scanningwithout dislodging the pad or causing an ultrasonic shadow at the pad'sedge. The pad may be held in place by positioning it beneath theabove-mentioned fabric covering.

Another methodology can be used to obtain the images, without the use ofa mechanized probe carrier, as described above. Again, the covering andnipple pad may be used.

As described above, the images are reviewed in a rapid sequentialfashion, imparting a sense of motion through the breast tissue. Thereviewer can observe or detect a disruption of the normal breastarchitecture through comparative image analysis or observation. Themethod has advantages over other ultrasound scanning techniques,including the following:

-   -   1) Parallel and contiguous images are obtained, optimizing the        coverage of the breast tissue and improving the appearance of        the images when viewed in a “movie-like” fashion.    -   2) The entire breast is imaged in a uniform and reproducible        manner.    -   3) The images may be maintained and reviewed singularly, in        strip form, or assembled to represent an entire breast, such as        3-D reconstruction.

Accordingly, an improved ultrasonic cellular tissue screening tool isdisclosed. Although embodiments and applications of this invention havebeen shown, it would be apparent to those skilled in the art that manymore modifications are possible without departing from the inventiveconcepts herein. The invention, therefore, is not to be restrictedexcept in the spirit of the appended claims.

1. A system for screening breast tissue, comprising: an ultrasoundprobe, wherein the probe is adapted to generate a series ofcross-sectional images of the breast tissue; a carrier adapted tosupport the ultrasound probe and to progressively move the probe overthe breast tissue; a pad to cover the nipple of the breast tissue,wherein the pad appears in the series of cross-sectional images toidentify the nipple as a reference point; and a fabric covering adaptedto hold the breast tissue and the pad in place as the probe is movedover the breast tissue.
 2. The system of claim 1, wherein the fabriccovering is capable of absorbing an ultrasonic coupling agent.
 3. Thesystem of claim 1, wherein the fabric covering includes a chain stitchedseam.
 4. The system of claim 1, wherein the fabric covering transmitsultrasonic energy with minimal interference.
 5. The system of claim 1,wherein the pad comprises a solid gel material.
 6. The system of claim1, wherein the pad is ultrasonically conductive.
 7. The system of claim1, wherein the pad has different ultrasonic characteristics than breasttissue.
 8. The system of claim 1, wherein the pad is lenticular-shaped.9. A system for screening breast tissue, comprising: an ultrasoundprobe; a carrier adapted to support the ultrasound probe and toprogressively move the probe over the breast tissue; a pad to cover thenipple of the breast tissue; and a fabric covering adapted to hold thebreast tissue and the pad in place as the probe is moved over the breasttissue, wherein the fabric covering is pre-impregnated with theultrasonic coupling agent.
 10. A system for screening breast tissue,comprising: an ultrasound probe; a carrier adapted to support theultrasound probe and to progressively move the probe over the breasttissue; a pad to cover the nipple of the breast tissue; and a fabriccovering adapted to hold the breast tissue and the pad in place as theprobe is moved over the breast tissue, wherein the fabric coveringprovides a pattern that can be used by an optical movement sensor.
 11. Asystem for screening breast tissue, comprising: an ultrasound probe; acarrier adapted to support the ultrasound probe and to progressivelymove the probe over the breast tissue to enable the probe to generate aseries of cross-sectional images of the breast tissue; a pad to coverthe nipple of the breast tissue, the pad having different ultrasoniccharacteristics than breast tissue and appearing in the images toidentify the nipple as a reference point; and a fabric covering adaptedto hold the breast tissue and the pad in place as the probe is movedover the breast tissue.
 12. The system of claim 11, wherein the padcomprises a solid gel material.
 13. The system of claim 11, wherein thepad is ultrasonically conductive.
 14. The system of claim 11, whereinthe pad is lenticular-shaped.
 15. A system for screening breast tissue,comprising: an ultrasound probe; a carrier adapted to support theultrasound probe and to progressively move the probe over the breasttissue to enable the probe to generate a series of cross-sectionalimages of the breast tissue; a pad to cover the nipple of the breasttissue; and a fabric covering adapted to hold the breast tissue and thepad in place as the probe is moved over the breast tissue, wherein thefabric covering is pre-impregnated with ultrasonic coupling agent andtransmits ultrasonic energy with minimal interference.
 16. The system ofclaim 15, wherein the fabric covering is capable of absorbing anultrasonic coupling agent.
 17. The system of claim 15, wherein thefabric covering provides a pattern that can be used by an opticalmovement sensor.
 18. The system of claim 15, wherein the fabric coveringincludes a chain stitched seam.